1. Field of the Invention
This type of coupling arrangement is generally known in the field of railway technology and is used in order produce a force-fit mechanical connection between two adjacent car bodies of a multi-member trainset. So that the coupling shaft can also pivot, for example when the trainset travels through curves, the drawgear is configured such that the coupling drawbar can realize horizontal and vertical swing as well as axial rotation. It is known that, given a rigidly supported coupling device, the impacts and vibrations which occur for example during the coupling procedure or when braking can lead to damaging of the vehicle and/or the coupling arrangement itself. To avoid these types of damages, it is necessary to limit the transmission of such impacts and vibrations and the like to the greatest extent possible. This is preferably achieved by providing the coupling arrangement with elastic cushioning means such as, for example, a tension/shock device to absorb such impacts. As an example, the drawgear can comprise a bearing bracket with a tension/shock device, whereby the tension/shock device elastically routes tractive and compressive forces up to a defined magnitude through the bearing bracket to the vehicle underframe. The objective is the absorption of energy by means of elastic deformation and thus avoiding overstressing of the underframe.
Further known in the field of rail vehicle technology is the use of multi-stage energy absorption devices. Same usually comprise a reversible energy absorption device as the primary stage, integrated for example as a tension/shock device in the drawgear or as a coupler spring in the coupling shaft of the central buffer coupling and which is designed to absorb impacts occurring during travelling, shunting and coupling. A second, secondary energy absorption device to absorb impact energy from excessive overrun impacts is moreover frequently provided in the form of two side buffers disposed at the outer edge of the respective car body's face side. The energy absorption devices are thereby configured such that the conversion of impact energy resulting from shunting accidents is effected as two transitioning processing operations, whereby the first stage is integrated in the central buffer coupling and the second stage is upstream the load-bearing car body structure.
Another approach provides for diverting the residual energy to energy absorption elements on the car body itself, for example friction elements, by means of a pre-set breaking point in the coupling arrangement after the energy absorption device provided for the coupling has been exhausted. However, this presupposes that the coupling shaft with the coupler head can be taken out of the power flow transmitted by the coupling arrangement upon a defined level of force being exceeded and thus allows an impact of the car bodies and the employing of energy absorption elements on the car body. The coupling shaft with the coupler head is usually removed from the power flow by having the coupling shear off at a pre-set breaking point such that most of the coupling arrangement is pushed backward into an area provided for the purpose in the underframe of the vehicle. A coupling's shearing function is usually attained by having the coupling shaft itself be attached to the drawgear or an articulation via the bearing bracket and via an external shearing element on the car body underframe which allows the shearing function. This design in which the bearing bracket is affixed to the underframe of the car body with external shearing elements does, however, presuppose that a corresponding opening be provided for the bearing bracket contact surface on the back side relative the car body's fixing plate in order to affix the external shearing elements from the back side to the underframe of the car body in mounting the drawgear and the bearing bracket associated with the drawgear on the respective face side of the car body. This has the consequence of making the fitting of external shearing elements a very complex and cost-intensive procedure. Moreover, a relatively large opening must in essence be provided in the fixing plate of the car body. The same difficulties also arise when the drawgear and the drawgear's associated bearing bracket are not mounted directly to the fixing plate of the car body but rather make use of an adapter plate.
2. The Prior Art
A perspective view of a drawgear 102 for a central buffer coupling for rail-mounted vehicles as known from the prior art is shown in FIG. 1. FIG. 2 shows the drawgear 102 of FIG. 1 in a sectional side view. This drawgear 102 is part of a central buffer coupling in which a tension/shock absorber 110 comprising an elastomeric spring element is integrated into the drawgear 102. It is hereby provided for the elastomeric spring element 110 to absorb the tractive/compressive forces up to a defined magnitude. Thus, the tractive/compressive forces occurring between the individual car bodies during normal travel are absorbed. When, however, the working load is exceeded, for instance when the vehicle collides with an obstacle, it can be that the energy absorption of the tension/shock absorber 110 provided in the drawgear 102 will not be sufficient. So that this excess impact-energy will not be transmitted directly to the vehicle underframe, subjecting same to extreme loads, the bearing bracket 104 of drawgear 102 is affixed to the car body, or the underframe of the car body respectively, by means of external shearing elements 108. This can especially be seen in FIG. 3 which shows a top plan view of the drawgear 102 of FIG. 1 in a mounted state on the underframe of the car body. The external shearing elements 108 respond upon the critical impact forces rated for the tension/shock absorber 110 being exceeded, whereupon they lose their function as fixing elements and the entire coupling assembly is taken out of the transmitted power flow.
Apart from the disadvantage that a relatively large opening 107 must be provided in the fixing plate 117 of the car body in order to mount the bearing bracket 104 of drawgear 102 to the vehicle underframe, the solution shown in FIG. 3 has the further disadvantage that the bearing bracket 104 can only be affixed to the car body with the external shearing elements 108 from the rear side of the fixing plate 117. Coupling assemblies in which bolting the drawgear from the rear side is not possible, for example because of a direct proximity to a bogie, cannot make use of such a shear-off solution for the coupling.